The research evidence from contingency management literature is unambiguous: larger-magnitude payment incentives are more influential to clients' behavior and more favored by clients than are lower-magnitude incentives (e.g., Kirby et al., 1998; Lamb et al., 1995; Silverman et al., 1999). This would seem to argue for the use of higher-magnitude payment incentives in research and clinical settings. As a result of these objections, researchers have often been forced to provide lower-magnitude, non-cash incentives to research participants, which the research evidence strongly suggests is likely to be a less effective modifier of human behavior (e.g., Cottler et al., 1995; Lamb et al., 1995; Stitzer et al., 1983). Prior to our own program of research, however, there was no direct evidence regarding whether large-magnitude incentives affect relapse rates or client perceptions of coercion. This is the first revision of the competing-continuation application for #R01-DA-13408, entitled Ethics of Participant Payment in Drug Abuse Research. The aims of that two-year study were to experimentally examine the effects of different incentive arrangements on: (1) likelihood of new drug use, (2) levels of perceived coercion, (3) rates of follow-up attendance and (4) satisfaction with the research study. In a two-by-three experimental design, we randomly assigned consenting drug abuse outpatient clients to receive $10, $40, or $70 in either cash or in a gift certificate for attending a 6-month follow-up research appointment. Importantly, our findings revealed that neither the mode nor magnitude of payment had a significant effect on rates of new drug use as measured by GCMS quantitative analyses, or on participants' perceptions of coercion. Our findings also revealed, not surprisingly, that higher-magnitude cash payments were associated with higher follow-up rates, as well as greater satisfaction with the research study and a greater willingness to participate in research studies in the future. The goal of this competing continuation application is to extend this innovative program of research by increasing the payment magnitudes to include $100, $130, and $160 increments. Our intent is to determine whether these higher magnitude incentives can be used in an ethical and safe manner, without precipitating new drug use or increasing perceptions of coercion among a drug using population. Testing these higher magnitudes of incentives is necessary to inform decisions about providing higher compensation for greater research burden (e.g., longer follow-ups, more invasive procedures), to begin to gather data on levels of payment that are often used in other contexts (e.g., contingency management protocols; employment, public assistance), and to determine whether higher magnitudes of payments contribute to higher follow-up rates. [unreadable] [unreadable] [unreadable]